From SBA:

Question: Is a business that was in operation on February 15, 2020 but had a change in ownership after February 15, 2020 eligible for a PPP loan?

Answer: Yes. As long as the business was in operation on February 15, 2020, if it meets the other eligibility criteria, the business is eligible to apply for a PPP loan regardless of the change in ownership. In addition, where there is a change in ownership effectuated through a purchase of substantially all assets of a business that was in operation on February 15, the business acquiring the assets will be eligible to apply for a PPP loan even if the change in ownership results in the assignment of a new tax ID number and even if the acquiring business was not in operation until after February 15, 2020. If the acquiring business has maintained the operations of the pre-sale business, the acquiring business may rely on the historic payroll costs and headcount of the pre-sale business for the purposes of its PPP application, except where the pre-sale business had applied for and received a PPP loan. The Administrator, in consultation with the Secretary, has determined that the requirement that a business “was in operation on February 15, 2020” should be applied based on the economic realities of the business’s operations.

https://home.treasury.gov/system/files/136/Paycheck-Protection-Program-Frequently-Asked-Questions.pdf