It is important to keep good records of your final searches in each database for transparency and reproducibility of your work. Systematic reviews generally utilise a PRISMA flow diagram for reporting the number of papers retrieved from each source before and after screening. This requires you to save the necessary information as you progress through your review, in order to fulfill the reporting requirements.
One method is to save copies of your search histories within each database. To do this you generally need to set up a free personal account in each relevant database - look for a link at the top of the main search page. Alternatively, you may choose to create a spreadsheet or search diary to record the details of your searches.