A "testing period" refers to a time frame during which something is examined, tried out, or evaluated to determine its quality, functionality, or effectiveness.
If you take two daily for a 300 mg dosage, you have a 90 day supply, which is the perfect testing period for magnesium. (supernaturalacnetreatment.com)
This can be viewed as testing period of final build in real life. (phonehorn.com)
After the beta testing period expires the service will be available by paying a monthly subscription fee. (book-marketing-expert.com)